The type locality for B. tenuiscapus is given as “Fillmore”. This is a city in Ventura County wherein an insectary facility was established, and it is not clear to me if specimens so labelled represent locally-collected taxa, or species brought in from other areas in biocontrol programs. Two Blepyrus species were imported into California for biocontrol programs, but both failed to establish: B. saccharicola imported from the southern USA in 1952 against Pseudococcus longispinus (Bartlett, 1978), and B. insularis imported from Mexico in 1966-67 against Ferrisia virgata (DeBach & Warner, 1969). Kerrich (1967) provided keys to species of this genus under both Blepyrus and Euryrhopalus.

Bartlett, B.R. 1978. Eriococcidae. Pp. 129-131 in Clausen, C.P. (ed.). Introduced parasites and predators of arthropod pests and weeds: a world review. United States Department of Agriculture, Agricultural Handbook 480: 545 pp.
Blackburn, T. & Cameron, P. 1886. On the Hymenoptera of the Hawaiian Islands. Memoirs of the Manchester Literary and Philosophical Society (3) 10: 194-245.
DeBach, P. & S. Warner. 1969. Importation and colonization of natural enemies of the striped mealybug, Ferrisia virgata, in California. Annals of the Entomological Society of America62: 1117-1119.
Gahan, A.B. 1942. Descriptions of five new species of Chalcidoidea, with notes on a few described species (Hymenoptera). Proceedings of the United States National Museum92: 41-51.
Howard, L.O. 1898. On some new parasitic insects of the subfamily Encyrtinae. Proceedings of the United States National Museum21: 231-248.
Kerrich, G.J. 1967. On the classification of the Anagyrine Encyrtidae, with a revision of some of the genera (Hymenoptera: Chalcidoidea). Bulletin of the British Museum (Natural History) Entomology) 20: 143-250.
Kerrich, G.J. 1982. Further systematic studies on Tetracnemine Encyrtidae (Hym., Chalcidoidea) including a revision of the genus Apoanagyrus. Journal of Natural History16: 399-430.